Transport and Metabolism of the Endogenous Auxin Precursor lndole-3-Butyric Acid

T Plant growth and morphogenesis depend on the levels and distribution of the plant hormone auxin. Plants tightly regulate cellular levels of the active auxin indole-3-acetic acid (IAA) through synthesis, inactivation, and transport. Although the transporters that move IAA into and out of cells are well characterized and play important roles in development, little is known about the transport of IAA precursors. In this review, we discuss the accumulating evidence suggesting that the IAA precursor indole-3-butyric acid (IBA) is transported independently of the characterized IAA transport machinery along with the recent identification of specific IBA efflux carriers and enzymes suggested to metabolize IBA. These studies have revealed important roles for IBA in maintaining IAA levels and distribution within the plant to support normal development.     

Monte Carlo simulations of the diffuse backscattering mueller matrix for highly scattering media

We have developed a Monte Carlo algorithm that computes all two-dimensional elements of the diffuse backscattering Mueller matrix for highly scattering media. Using the Stokes-Mueller formalism and scattering amplitudes calculated with Mie theory, we are able to consider polarization-dependent photon propagation in highly scattering media, including linearly and circularly polarized light. The numerically determined matrix elements are compared with experimental data for different particle sizes and show good agreement in both azimuthal and radial direction.     

High-efficiency binary phase-transmission-grating using e-beam lithography

Abstract

Rigorous coupled-wave analysis indicates that diffraction efficiencies greater than 99% are feasible for dielectric phase-gratings with a rectangular profile. The use of rectangular rather than blazed profiles implies simplified fabrication techniques, since deep-etch submicrometre structuring techniques can be utilized. We identify several parameter combinations with high diffraction efficiencies using rigorous coupled wave analysis, demonstrate experimentally diffraction efficiencies of 94% in a Bragg mount configuration at a wavelength of 543 nm and discuss the influence of substrate thickness on the transmitted light intensities. A direct writing electron-beam lithography fabrication process gives wide flexibility in design realization.     

Bücherschau

Ohne Zusammenfassung VDI     

A TQM PROCESS FOR SYSTEMS INTEGRATION Getting the Most from COTS Software

Many companies are shopping for commercial off-the-shelf software to avoid the high costs and lengthy development time associated with building their own systems. This article discusses how methods of total quality management (TQM) can be used to better integrate large-scale commercial software purchases.     

Bioactive and nuclease-resistant L-DNA ligand of vasopressin

In vitro selection experiments have produced nucleic acid ligands (aptamers) that bind tightly and specifically to a great variety of target biomolecules. The utility of aptamers is often limited by their vulnerability to nucleases present in biological materials. One way to circumvent this problem is to select an aptamer that binds the enantiomer of the target, then synthesize the enantiomer of the aptamer as a nuclease-insensitive ligand of the normal target. We have so identified a mirror-image single-stranded DNA that binds the peptide hormone vasopressin and have demonstrated its stability to nucleases and its bioactivity as a vasopressin antagonist in cell culture.